New cat owner here.

Sounds fishy. Factory new cat and motor? If not, definitely the pump.

Nope – 5psi at idle sounds good. Flush jackplate is not at all high – most run 3/8″ to 1/2″ higher. Without a smartcraft digital trim the readouts vary – but mine doesnt like to be above 1/4 trim on the gauge or the pressure starts dropping ( but Im higher on the plate). 8-10psi fully tucked is low. You need to let them run the boat and verify for themselves. The water inlets on the LU prefer to be square to the water flow. Too much or not enough trim will drop the water pressure. Turning will drop it some as well and needs a bump down or two on the trim switch. Let your dealership tell you whats going on.BTW – after 8 years and hundreds of hours running mine – I rarely have the analog trim gauge above 1/4 – 1/3 of the dial sweep at WFO. 100% will have the motor at full tilt and out of the water. 1/2 or less is full trim. The Sabre hull does not like a lot of trim to run – air cushion under the front and water flow under the pad gives you most of your lift. Past its “happy place” and youre just throwing water to look impressive – it costs you speed, fuel, and water pressure. Fast on a Sabre has the rooster tail long and low. Unlike most hulls – If its cowl high youre over trimmed. I trim based on gps speed and water pressure. Max speed comes in well before the WP drops below 13lbs.

At 5100rpms – youre too slow to chine walk or get significant torque. The 8-10lbs at full tuck does seem too low – but what rpms were you running? It never hurts to have it looked at to make sure theres not an issue with thermostats or such in the cooling system. Normally a high temp will trigger the guardian which will drop you to 1000 rpms until it cools off. They can read the computer and tell. I really wish the dealerships would tell folks – keep the motor tucked for 5 hours and call us. Well go out with you after break-in and help you get to know the boat. For one – it would allow them to sniff out issues. Secondly – it would give you a better handle on what to expect from the hull and speed your learning process. Any BCB is a performance hull and it has a longer learning curve than the cookie cutter brands. On this one – when you trim will be progressive to how fast youre going. Ill bump it up a little once its leveled off until the hull starts to lift and loosen – then I start trimming by WP and gps speed. Theres an optimal trim point at really every speed and its load dependent. Its not a break over and trim till it stops kind of hull. Youll be amazed at how flat the hulls running at max speed. Nose high pictures helps to sell boats, but in real life thats not at all optimal.